Tasers 'are very effective tool, says Police Federation

New figures show the use of Tasers by police in England and Wales more than doubled between 2009 and 2011.

Human rights charity Amnesty International says the rising number of officers with stun guns is a grave concern.

But Steve White, vice chairman of the Police Federation, said they were an effective tool.

He said offenders were more likely to be compliant if they saw an officer with a Taser.